(a) Field of the Invention
The present invention relates to improvements in internal combustion engines and more particularly to improvements in cylinder heads therefor.
(b) Description of the Prior Art
A number of prior art internal combustion engines perform better than others as a result of a number of improvements made in their design, however, these improved engines still do not perform in a truly efficient manner. Applicant, through an extensive program of testing, has identified two major areas which contribute to this, namely inadequate cooling in certain parts of the engine and particularly in the case of two stroke engines, incomplete and thus inefficient combustion of the fuel, i.e., fuel-air mixture.
Regarding a more specific area, research has shown limited development has taken place over the years in the field of two stroke marine type engines, i.e., with a view to improving their operating efficiency, notwithstanding their common use in competitive sporting activities. The present invention specifically addresses this area.
Turning first to the question of inadequate engine cooling. Tests have revealed one of the hottest parts of an internal combustion engine during operation thereof, is the area of the mounting of the sparkplug, i.e., the threaded mounting portion, normally residing in the head of the engine. Although various designs of cylinder head have been produced, having for example, fluid cooling channels therein, none have been designed to efficiently cool this hottest part of the head. Reference is made for example, to McDonald's U.S. Pat. No. 1,378,254, dated May 17, 1921, showing coolant channels in the head in the vicinity of the sparkplug. In such instance, the threaded mounting of the sparkplug is located remote from the coolant channels. A further example of prior art engine having coolant channels in the head, located remote from the sparkplug threaded mounting portion, is Chard's U.S. Pat. No. 3,003,485, dated Oct. 10, 1961. A more recent example of the prior art head design having coolant channels therein, is that disclosed in Kueny's U.S. Pat. No. 3,667,431, dated June 6, 1972. Although the fluid channels are located adjacent the deemed hottest portion of the sparkplug, they do not permit fluid flow completely around the same. Furthermore, in this design, coolant flow is restricted by requiring it to move in a first direction and then in a reverse second direction, thus to enter and exit at one side or one end of the head. the evident drawback with this design is that the coolant removes heat from the first sparkplug and has it reapplied together with heat from the second sparkplug, upon exiting from the head. The situation is compounded when more than two cylinders and accompanying sparkplugs are present.
Turning now to the question of incomplete combustion of fuel in the combustion chamber of two stroke engines. Tests have revealed, the incomplete burning of the fuel occurs as a result of a number of things, including inadequate igniting means for the fuel, inadequate directing of the fuel within the combustion chamber for its ignition and incorrect positioning of the igniting means within the combustion chamber, also incorrect positioning of the igniting means relative to the fuel entry position into the chamber. Furthermore, lack of means to ensure proper movement of the fuel to obtain combustion.
Although various designs of engines and various designs of cylinder heads have been produced, having substantial fuel igniting means comprising two or more sparkplugs per cylinder, for example, such have not provided, in the case of two stroke engines, efficient combustion of the fuel in the combustion chamber. Although four cycle engine combustion chamber designs exist which include a contour feature similar to that of the present design discussed hereinafter, such is for an entirely different purpose, i.e., to enhance four cycle operation.
As mentioned above, the use of two sparkplugs in the combustion chamber of an internal combustion engine is well known, as exemplified by Utz's U.S. Pat. No. 1,015,101, dated Jan. 16, 1912. This reference, however, discloses the use of two sparkplugs per cylinder in a four cycle engine, i.e., one employing inlet and outlet valves, providing combustion of the fuel in a manner contrary to that of the present invention, as discussed hereinafter. Multi sparkplugs per cylinder is also disclosed in Woolson's U.S. Pat. No. 1,532,292, dated Apr. 7, 1925. The use of two sparkplugs per cylinder in aircraft engines is also known. In such instances, the second plug is supplied as a safety measure, namely to provide improved reliability, thus as a backup should the one sparkplug fail. Harper's U.S. Pat. No. 2,025,202 dated Dec. 24, 1935, discloses a two-cycle engine having two sparkplugs in its cylinder, however, the sparkplugs are not of similar type and are not arranged whereby both extend into the combustion chamber via the wall thereof, to afford efficient and desirable combustion effect.